The inventive concept relates to memory devices, and more particularly, to memory devices which reduce or prevent internal and external commands input thereto from overlapping with one another, and to systems that include such memory devices.
Semiconductor memory devices may be classified into volatile memory devices, e.g., dynamic random access memory (DRAM) and static random access memory (SRAM), and non-volatile memory devices, e.g., phase change random access memory (PRAM), resistive random access memory (RRAM), and magnetic random access memory (MRAM).
If read commands are input to a semiconductor memory device at intervals that are shorter than predetermined intervals, then a read operation that is being performed according to a previous read command should be stopped and be newly performed.
Furthermore, in order to operate semiconductor memory devices that employ error correction coding (ECC) techniques, there is a need to develop a technique of operating the semiconductor device according to at least two read commands, e.g., an internal read command and an external read command, or at least two internal read commands, while preventing the at least two commands from being affected by each other.